Patent GB-972568-A (GB)
Title: Cinematographic method and apparatus
IPC: G03B41/08
Filed: 1962-05-01
Abstract: 972,568. Lenticular cinematography. INTERNATIONAL POLAROID CORPORATION. May 1, 1962 [May 19, 1961], No. 16669/62. Headings G2C and G2E. A method of cinematography comprises directing light through an anamorphotic imageforming optical system having a greater degree of magnification in a first of two mutually perpendicular directions, positioning a lenticular screen having a multiplicity of cylindrical lens elements at or adjacent to an image surface of the optical system with the axes of curvature of the lens elements extending in the second of the mutually perpendicular directions, interposing an aperture in the path of light transmitted by the optical system and the screen, producing, during exposure of the recording medium, a sequence of line images representing aspects of the aperture and of the scene being depicted behind each of the lens elements on the surface of a photographic recording medium positioned at the image plane of the lens elements by moving the recording medium and the optical system relative to one another in the second direction while simultaneously somoving the aperture and the recording medium relative to one another as to move the line images relative to said surface of the recording medium in the first direction, and displacing the image formed by the optical system relative thereto in the same direction as the recording medium is moved relative to the optical system to prevent motion of the last-mentioned image in the second direction relative to the recording medium. In a preferred embodiment (Figs. 1a and 1b), an anamorphotic objective comprises two crossed cylindrical lenses 10, 12, the cylindrical axis of lens 10 being horizontal and that of lens 12 being vertical. The objective, which produces an elongated image with greater magnification (e.g. 10: 1) in the vertical than the horizontal direction is designed to exhibit astigmatism. A lenticular screen 14 comprising minute (e.g. 0. 006 inch diameter) cylindrical lens elements arranged horizontally is disposed at or adjacent to an image surface of the objective 10, 12. A layer 16, for example of gelatino silver halide emulsion, may be supported on the rear of screen 14 or on a separate support, and is located at the focal surface of the lenticules of the screen 14. A horizontally extending slit aperture 18 is movable in the vertical direction behind the lens 10 and as it is moved across the lens, the layer 16 is exposed by a series of line images. In order that the exposure process may be continuous, the layer 16 is moved with uniform velocity in the direction of the lenticules and an optical compensater (for example a variable prism 22 comprising a fixed part and a movable part) is provided to prevent relative motion between the image produced by the objective and the layer 16 in the direction of the lenticules. Further, a succession of movable parts for compensator 22 and a succession of slit apertures 18 each movable uniformly and continuously in synchronism with the movement of the layer 16 in known manner, are provided in order that successive areas of the layer 16 may be exposed continuously. A simple cover blade type of shutter may be provided to prevent fogging of the layer 16 before and after a sequence of exposures. In a first modification, in which the layer 16 must be separate from the screen 14, a single slit aperture 18 is held stationary and the layer 16 is moved in a direction inclined slightly to the lenticules so as to have a component of velocity in the vertical direction. The tangent of the angle of inclination is made equal to the lenticular width divided by the image width whereby said component in the vertical direction produces a result equivalent to the movement of the aperture in the previous embodiment. In this first modification, an alternative optical compensator may be used comprising, as shown in Fig. 3, a pair of contra rotating discs 24 each made up of a plurality of sector-shaped wedge prisms 26. The stationary slit aperture is shown at 28. In a second modification, aperture 18 and compensator 22 are replaced by a narrow elongated plane mirror which defines the aperture of the system and is moved to simulate both the movement of aperture 18 and the effect of the compensator 22. In a third modification, a slit aperture, which is moved linearly in the manner of aperture 18, replaces the front lens 10 of the objective 10, 12. A formula for the width of the slit is given. The other lens 12 may optionally also be replaced by a stationary slit aperture. Optical compensation in this modification is obtained by a rotating plane mirror. Specifications 421,120 and 905,244 are referred to.